The present invention relates to the general field of household electric appliances, and more particularly cooking appliances of the oven or toaster type.
The present invention concerns a safety device permitting, in particular, the detection of smoke and of performance of a certain number of functions relating to operating safety of the appliances under various utilization conditions.
The present invention thus permits construction of a device for detection of smoke as well as bodies having a certain opacity to light, these including objects and a user's hand, and capable of controlling the operation of household electric appliances, of the toaster type, by initiating a stop-eject function or interruption of the supply of current to heating elements.
It is already known to provide smoke detection devices for use in microwave ovens. Thus, U.S. Pat. No. 5,493,119 describes a detector for the presence of smoke or vapors, or fumes, in a microwave chamber. The detector comprises a light emitting diode as well as two optical receivers of the phototransistor type, permitting reception of a signal by transmission, reflection or diffusion when smoke or steam passes through the detector, and more precisely through the detector analysis chamber, this chamber being isolated optically with respect to ambient light or any other parasitic light source. This document also describes analyzing electronics for recognizing an increase in the intensity of the signal on one of the detectors and simultaneously a decrease in the intensity of the signal on the other detector.
Such a detector presents the drawback of not being able to operate correctly or in an effective manner when it is subjected to parasitic light or radiation. Its precise positioning, sheltered from all parasitic radiation, is thus indispensable. This gives rise to particular mounting constraints, and increased fabrication costs, to the extent that smoke must be channeled and brought into a detection chamber.
It is also known, as disclosed in French Patent Document FR-A-2 609 342, to provide a device which includes a chamber into which smoke penetrates, a light emitting diode and a phototransistor. This document also describes means permitting development of an outlet signal from the phototransistor, this being for the purpose of detecting attenuation of a signal emitted by the light emitting diode. Such a device presents the disadvantage that it comprises an analysis chamber in which an optical system is arranged, this being for the purpose of preventing the influence of ambient or parasitic light on the photodiode or the optical receptor. Another disadvantage resulting therefrom is that the smoke must be channeled and led into the analysis chamber.